Reduced-order model for the dynamical analysis of complex structures with a high modal density

Abstract : The low-frequency (LF) band is classically characterized by the presence of relatively well separated resonances associated with global elastic modes (non local elastic modes). In this work, we are interested in predicting the dynamical response of complex structures presenting several structural scales (for instance, the presence of flexible panels connected to a stiff master structure). For such structures, a high modal density can be observed in the low- and in the medium-frequency bands. This high modal density for the low-frequency band is not the usual case considered by the modal analysis which would require a large number of elastic modes to represent the response with a good accuracy. In this context, a new methodology is introduced for constructing a small-size reduced-order basis adapted to span the global displacements space.